Hi Anders;
Yes and No.
Yes where there are different major versions involved as they will have separate folders and more importantly unique DLL's. However, some DLL's are not unique within any combination of PB installations!
Normally the answer is No for PB revisions as the PB installer will look for an existing major version and just perform an "update in place" once it sees the current release for a "revision" installed.
However on the "no" side, there are ways to do this. I have a session next week at the Elevate2018 Conference on IDE Tips & Tricks where I will cover off the above circumstances and safely show you how to run multiple versions & revisions and to eliminate any DLL conflicts 100%.
Regards ... Chris